Study area This study was conducted at Keshabpur Upazila (a sub–county) under Jessore District in Bangladesh. Keshabpur is located approximately between 220 25/ to 230 N and 890 25/ to 890 38/ E with an area of 259 km2. The Upazila (UP) is bounded by Manirampur UP to the north and Tala and Dumuria UPs to the south. Dumuria UP also covers the south-east part while Kalarua UP is to the west; the main rivers are the Kapotaksho and the Hariar. The major plant species of the study area are: coconut (Cocos nucifera), betel nut (Areca catechu), date palm (Phoenix sylvestris), mango (Mangifera indica), jackfruit (Artocarpus heterophyllus), mast tree (Polylthia longifolia), mahogany (Swetenia mahogani), banyan (Ficus benghalensis), dumur (Ficus glomerata), and peepal tree (Ficus religiosa). Annual temperature varies from 11- 330 C,rainfall 1,524 to 1,752 mm and humidity is 78 % (Bari 1979). Study group The fieldwork started in September 2009 on two common langur groups, designated BBT-1 and BBT-2, in two villages (Brahmakati and Baliadanga) of Keshabpur UP. In September 2009 BBT-1 contained 15 members (1 adult male, 7 adult females, 1 juvenile, and 6 infants), while group BBT-2 comprised 21 members (1 adult male, 9 adult females, 4 juveniles, and 7 infants). Fieldwork was done on both BBT-1 and BBT-2 during September and October 2009, but in late October 2009 the entire BBT-2 troop was found to have left these two villages. The troop was absent from the study area during the subsequent months. We learned from the local people that BBT-2 was not a permanent resident of the two villages. Their visit to the area seems to be irregular. Hence, we had to drop BBT-2 from the study plan, because of the uncertain availability of the troop in the study area. BBT-1, on the other hand, was a permanent resident of the two villages. The availability of suitable trees, food, and positive attitudes of local people to keep them in the vicinity, possibly helped this group to live in the area. Another factor, which helped them in their permanent stay in these two villages, is that they could survive without the food supply programme from a Government project. Hence, the study plan was revised in November 2009, and the fieldwork was confined to only BBT1 for the remaining period. From November 2009 the fieldwork continued monitoring the activity budget and feeding ecology of four selected members of the BBT-1; one adult male (dominant male, am-1), two adult females (af-1, af-2), and one sub–adult female (who by February 2010 became an adult female, hence, sgaf). The af-1 and af-2 were clearly distinguishable by difference in size and by some marks of physical appearance. The dominant male and the sgaf were themselves quite easily identifiable. Activity budget and feeding ecology These four focal langurs were closely observed from dawn to dusk every month from September 2009 to August 2010, using the scan sampling method (Altmann 1974) for focal individuals. The observation included their total activity budget and, specially, their food choice and feeding ecology. The activity pattern of the focal langurs was divided into four aspects - feeding, resting, moving, and others. These four terms were defined as follows: (1) feeding included handling of food, intake for mastication, chewing and swallowing of food items; (2) resting means cessation of all sorts of movements and motions; (3) moving behaviour means all activities such as changing place and position; and (4) ‘other activities’ means grooming, monitoring, copulatory behaviour and all actions and behaviours beyond the purview of the main three behavioural categories. Explanation of the categories of langur food items Food items were categorised into five: (1) young leaves; (2) mature leaves, including leaf petiole; (3) flowers, including floral bud, complete flower, and also inflorescence; (4) fruits (fruit buds, immature and mature fruits, seeds, and also fruit coatings); and (5) ‘other food items’, this includes fungus, bamboo shoot, barks (rain tree), and condensed secretion (gum) of some trees (e.g., jeol, Lannae coromendelica) and, very unusually, soil during the winter. Study plan for activity budget For the study of activity budget four days dawn-todusk observations were carried out each month from September 2009 to August 2010, but deviations from this plan did occur due to unavoidable reasons. For example, only one-day observation made in September 2009, and two days in February 2010 and three days in October 2009, January, March, June, and July of 2010. The following observation plan was normally followed. On the first day of the four-day sampling in November 2009, observation was started at dawn (0630 h) on the activities of am-1. At every 10th minute the activity of the male was observed, e.g., feeding and, if lasting for five seconds or more, the action was recorded. If the male went out of sight at a scheduled time, the reading was not recorded. In this way observation and recording of activities were continued up to dusk of the first day. At dawn of the second day of that sampling month (e.g., November 2009) fieldwork was started with the first focal female, af-1. The same procedure and recording plan, was followed, but the second day’s observation plan was of a fundamental difference than that of the male. Hence, if af-1 went out of sight at a particular 20 minutes interval the recording was stopped and the other adult female individual (af-2) was selected as the focal animal. Similarly, the third and fourth days’ work were on af-2 and sgaf, respectively, following the same procedure as for af-1. Vegetation and abundance of food plants in the study area To record types and abundance of vegetation and food plants of the langur, the following study method was carried out. A 50 x 50 m grid was first marked, and then the number of food trees (of langur), non-food trees, and food plants belonging to the group - herbs, shrubs, and climbers were counted. Counts of 28 grids were selected randomly in the home range area of the langurs.